Merge pull request #18 from bartlomieju/decode_data_row

First pass at decoding data rows

Author: bartlomieju

connection.ts

@@ -36,7 +36,7 @@ import { parseError } from "./error.ts";
 import { ConnectionParams } from "./connection_params.ts";
 
 
-enum Format {
+export enum Format {
     TEXT = 0,
     BINARY = 1,
 }
@@ -60,7 +60,7 @@ export class Message {
 }
 
 
-class Column {
+export class Column {
     constructor(
         public name: string,
         public tableOid: number,
@@ -204,8 +204,6 @@ export class Connection {
         if (responseCode !== 0) {
             throw new Error(`Unexpected auth response code: ${responseCode}.`);
         }
-
-        console.log('read auth ok!');
     }
 
     private async _authCleartext() {
@@ -312,7 +310,7 @@ export class Connection {
                 // data row
                 case "D":
                     // this is actually packet read 
-                    const foo = this._readDataRow(msg, Format.TEXT);
+                    const foo = this._readDataRow(msg);
                     result.handleDataRow(foo)
                     break;
                 // command complete
@@ -512,7 +510,7 @@ export class Connection {
                 // data row
                 case "D":
                     // this is actually packet read 
-                    const rawDataRow = this._readDataRow(msg, Format.TEXT);
+                    const rawDataRow = this._readDataRow(msg);
                     result.handleDataRow(rawDataRow)
                     break;
                 // command complete
@@ -563,7 +561,7 @@ export class Connection {
         return new RowDescription(columnCount, columns);
     }
 
-    _readDataRow(msg: Message, format: Format): any[] {
+    _readDataRow(msg: Message): any[] {
         const fieldCount = msg.reader.readInt16();
         const row = [];
 
@@ -575,12 +573,8 @@ export class Connection {
                 continue;
             }
 
-            if (format === Format.TEXT) {
-                const foo = msg.reader.readString(colLength);
-                row.push(foo)
-            } else {
-                row.push(msg.reader.readBytes(colLength))
-            }
+            // reading raw bytes here, they will be properly parsed later
+            row.push(msg.reader.readBytes(colLength))
         }
 
         return row;

decode.ts

@@ -0,0 +1,169 @@
+import { Oid } from "./oid.ts";
+import { Column, Format } from "./connection.ts";
+
+
+// Datetime parsing based on:
+// https://github.com/bendrucker/postgres-date/blob/master/index.js
+const DATETIME_RE = /^(\d{1,})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})(\.\d{1,})?/;
+const DATE_RE = /^(\d{1,})-(\d{2})-(\d{2})$/;
+const TIMEZONE_RE = /([Z+-])(\d{2})?:?(\d{2})?:?(\d{2})?/;
+const BC_RE = /BC$/;
+
+function decodeDate(dateStr: string): null | Date {
+    const matches = DATE_RE.exec(dateStr);
+
+    if (!matches) {
+        return null;
+    }
+
+    const year = parseInt(matches[1], 10);
+    // remember JS dates are 0-based
+    const month = parseInt(matches[2], 10) - 1;
+    const day = parseInt(matches[3], 10);
+    const date = new Date(year, month, day);
+    // use `setUTCFullYear` because if date is from first
+    // century `Date`'s compatibility for millenium bug
+    // would set it as 19XX
+    date.setUTCFullYear(year);
+
+    return date;
+}
+/**
+ * Decode numerical timezone offset from provided date string.
+ * 
+ * Matched these kinds:
+ * - `Z (UTC)`
+ * - `-05`
+ * - `+06:30`
+ * - `+06:30:10`
+ * 
+ * Returns offset in miliseconds.
+ */
+function decodeTimezoneOffset(dateStr: string): null | number {
+    // get rid of date part as TIMEZONE_RE would match '-MM` part
+    const timeStr = dateStr.split(' ')[1];
+    const matches = TIMEZONE_RE.exec(timeStr);
+
+    if (!matches) {
+        return null;
+    }
+    
+    const type = matches[1];
+
+    if (type === "Z") {
+        // Zulu timezone === UTC === 0
+        return 0;
+    }
+
+    // in JS timezone offsets are reversed, ie. timezones
+    // that are "positive" (+01:00) are represented as negative
+    // offsets and vice-versa
+    const sign = type === '-' ? 1 : -1;
+
+    const hours = parseInt(matches[2], 10);
+    const minutes = parseInt(matches[3] || "0", 10);
+    const seconds = parseInt(matches[4] || "0", 10);
+
+    const offset = (hours * 3600) + (minutes * 60) + seconds;
+    
+    return sign * offset * 1000;
+}
+
+function decodeDatetime(dateStr: string): null | number | Date {
+    /**
+     * Postgres uses ISO 8601 style date output by default:
+     * 1997-12-17 07:37:16-08
+     */
+
+    // there are special `infinity` and `-infinity` 
+    // cases representing out-of-range dates
+    if (dateStr === 'infinity') {
+        return Number(Infinity);
+    } else if (dateStr === "-infinity") {
+        return Number(-Infinity);
+    }
+
+    const matches = DATETIME_RE.exec(dateStr);
+
+    if (!matches) {
+        return decodeDate(dateStr);
+    }
+
+    const isBC = BC_RE.test(dateStr);
+
+    
+    const year = parseInt(matches[1], 10) * (isBC ? -1 : 1);
+    // remember JS dates are 0-based
+    const month = parseInt(matches[2], 10) - 1;
+    const day = parseInt(matches[3], 10);
+    const hour = parseInt(matches[4], 10);
+    const minute = parseInt(matches[5], 10);
+    const second = parseInt(matches[6], 10);
+    // ms are written as .007
+    const msMatch = matches[7];
+    const ms = msMatch ? 1000 * parseFloat(msMatch) : 0;
+    
+
+    let date: Date;
+
+    const offset = decodeTimezoneOffset(dateStr);
+    if (offset === null) {
+        date = new Date(year, month, day, hour, minute, second, ms);
+    } else {
+        // This returns miliseconds from 1 January, 1970, 00:00:00, 
+        // adding decoded timezone offset will construct proper date object.
+        const utc = Date.UTC(year, month, day, hour, minute, second, ms);
+        date = new Date(utc + offset);
+    }
+
+    // use `setUTCFullYear` because if date is from first
+    // century `Date`'s compatibility for millenium bug
+    // would set it as 19XX
+    date.setUTCFullYear(year);
+    return date;
+}
+
+function decodeBinary() {
+    throw new Error("Not implemented!")
+}
+
+const decoder = new TextDecoder();
+
+function decodeText(value: Uint8Array, typeOid: number): any {
+    const strValue = decoder.decode(value);
+
+    switch (typeOid) {
+        case Oid.char:
+        case Oid.varchar:
+        case Oid.text:
+        case Oid.time:
+        case Oid.timetz:
+            return strValue;
+        case Oid.bool:
+            return strValue[0] === "t";
+        case Oid.int2:
+        case Oid.int4:
+        case Oid.int8:
+            return parseInt(strValue, 10);
+        case Oid.float4:
+        case Oid.float8:
+            return parseFloat(strValue);
+        case Oid.timestamptz:
+        case Oid.timestamp:
+            return decodeDatetime(strValue);
+        case Oid.date:
+            return decodeDate(strValue);
+        default:
+            throw new Error(`Don't know how to parse column type: ${typeOid}`);
+    }
+}
+
+export function decode(value: Uint8Array, column: Column) {
+    if (column.format === Format.BINARY) {
+        return decodeBinary();
+    } else if (column.format === Format.TEXT) {
+        return decodeText(value, column.typeOid);
+    } else {
+        throw new Error(`Unknown column format: ${column.format}`);
+    }
+}